Anthropic CEO Dario Amodei pushed back on claims that his AI startup supports a ban on open-weight models to protect its competitive position, after Anthropic was notably absent from a letter signed by many leading AI firms.

Leading companies in the AI sector, including Nvidia, Palantir and others, took part in the letter and announced a partnership in the Open Secure AI Alliance, which aims to develop and share more open technologies to improve security in the AI era, given that risks can arise from both open and closed models. The exchange underscores an active debate in the AI industry over how much openness best supports safety, access and competition as model capabilities advance.

Amodei wrote in a post on Anthropic's website, "Anyone who has read my past writing should know that I don't regard such bans as a useful measure, but let me state it clearly so that there is no doubt: Anthropic has never advocated for a ban on open-weight models."

"But I don't agree with the letter's assertions that open-weights models necessarily make it easier to develop safeguards or that broad access to capabilities necessarily helps defenders more than attackers. It seems at least as likely to me that the opposite will be true," he wrote, adding that biological weapons may have an edge over the defenses against them.

Amodei said he views open-weight models that do not have dangerous capabilities as a public good because their cost is limited to the computer needed to operate them, and they can provide value to businesses, developers and researchers.

He also said he agreed with much of the open letter, particularly its emphasis on the value of open-weights in expanding access to the AI economy, strengthening competition and giving customers more control.

"To summarize my and Anthropic's position, we have not and are not advocating for a ban on open-weights models as a category. We should instead focus on keeping powerful chips out of authoritarian hands, stopping industrial-scale distillation, and requiring safety testing of all sufficiently capable models, open and closed," Amodei wrote.

Amodei's letter came hours after Palantir CEO Alex Karp, whose company signed the letter supporting the use of open-weight AI models, said in an exclusive interview on FOX Business Network's "The Claman Countdown" that resistance to competition could leave the tech industry less dynamic, similar to Europe.

Karp said he is "not anti-Anthropic" or opposed to all closed models, but added, "If you want to win, you have to compete on the battlefield."

"Our job has to be to have the best AI in the world, if you're going to actually say we're going to restrict all the products to U.S. commercial, but they're not going to be restricted abroad, which they're not, you're de facto setting up a two-stage thing where no one can claim we have the best products in the world. It's complete insanity," Karp said.

"We are building our platform in the U.S. government on the open-weight side with Nvidia. We can get the best performance in the world with a totally American company, using American open-weight companies and American GPUs. We don't have to hide behind some kind of fake thing," Karp said.